CST

Photonic Crystal Simulation

Photonic crystals are periodic structures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the motion of electrons. The non-existence of propagating EM modes inside the structures at certain frequencies introduces unique optical phenomena such as low-loss-waveguides, omni-directional mirrors and others. The part of the spectrum for which wave propagation is not possible is called the optical band-gap.  The underlying physical phenomenon is based on diffraction. Therefore, the lattice constant of the photonic crystal structure has to be in the same length-scale as half the wavelength of the electromagnetic wave. Figure 1 shows a one dimensional periodic structure which is investigated by using the transient solver of CST MICROWAVE STUDIO® (CST MWS).


1 dimensional periodic structure
Figure 1: 1 dimensional periodic structure

The rods are made from GaAS with refractive index of 3.4 and with an edge length of about 180 nm. The lattice spacing between the rods is 760 nm. As a first step, the transmission of a plane wave through this crystal is simulated.


single column of the array
Figure 2: single column of the array

By using appropriate boundary and symmetry conditions it is sufficient to calculate a single column of this array as shown in Figure 2. In this case, the structure is driven by a waveguide port. Due to the magnetic and electric symmetry planes, the excitation mode is a  normally incident plane wave.


Transmisson vs. wavelength
Figure 3: Transmisson vs. wavelength

Figure 3 shows the transmission through the structure. Between 1400 and 2200 nm the transmission is zero. In this bandgap region no wave propagation in possible.


Wave Propagation at frequencies below the band gap
Figure 4: Wave Propagation at frequencies below the band gap

Figures 4-6 shows the propagation of a plane wave at normal incident for at different frequencies.


Wave propagation at frequencies in the band gap
Figure 5: Wave propagation at frequencies in the band gap


Wave Propagation at frequencies above the band gap
Figure 6: Wave Propagation at frequencies above the band gap

The information obtained about the photonic band gap can be used to design optical devices. Figure 7 shows the periodic PBG structure as described above. A line defect is introduced and the structure is excited with a electromagnetic wave at band gap frequencies. The wave can only propagate inside the line defect.


Photonic Crystal with line defect
Figure 7: Photonic Crystal with line defect

Finally, Figure 8 shows the wave propagation inside the Photonic crystal with a bent defect. Again, the structure is driven with a time harmonic signal. The signal frequency is inside band gap of the crystal. Consequently, the wave propagates inside bend defect.


Photonic crystal with a bend defect
Figure 8: Photonic crystal with a bend defect

This article demonstrates the possibilities to model photonic crystals with CST MWS by using the transient solver. The general characterization would also be possible with the Frequency Domain and Eigenmode Solver of CST MWS by applying periodic boundary conditions.


CST Article "Photonic Crystal Simulation"
last modified 15. Jan 2007 5:42
printed 6. Mar 2015 6:53, Article ID 296
URL:

All rights reserved.
Without prior written permission of CST, no part of this publication may be reproduced by any method, be stored or transferred into an electronic data processing system, neither mechanical or by any other method.

Feedback

22 of 28 people found this article useful

Did you find this article useful?

Other Articles

3D Non-linear Transient Simulation of an SF6 550 kV 3-Phase Gas Insulated Bus

3D Non-linear Transient Simulation of an SF6 550 kV 3-Phase Gas Insulated Bus
The combination of non-linear materials and eddy currents leads to a problem which cannot be solved with a steady-state eddy current solver. A transient solver is required and and inherently includes the feature that arbitrary time signals can be used for the excitation. The CST EM STUDIO® (CST EMS) transient solver allows such a simulation to be carried out. In this case, a Gas insulated Bus under short circuit conditions is investigated. The forces and losses on the bus bars can be calculated as a function of time. Read full article..

CST MWS Simulation of the SARAF RFQ 1.5 MeV/ nucleon proton/deuteron accelerator

CST MWS Simulation of the SARAF RFQ 1.5 MeV/ nucleon proton/deuteron accelerator Document type
J. Rodnizki, Soreq NRC - The SARAF RFQ is a four rod RFQ, operating at a frequency of 176 MHz, designed to bunch and accelerate a 4 mA deuteron/proton beam from 20 keV/nucleon DC up to 1.5 MeV/nucleon CW. Read full article..

Chip Package Board: Constraint Driven Co Design

Chip Package Board: Constraint Driven Co Design
Memory interfaces have single-ended data rates in the 1GHz-plus range and serial links are running upwards of 10 gigabits per second. A precise analysis of each of these signals is required at silicon, package and board level. The design and optimization performed on each one of these interconnection levels must be done in a global context. This webinar proposes a global methodology which combines three dimensional (3D) electromagnetic (EM) analysis for PCB and package with chip power switching macro-modeling. Difference between segmentation approach (where silicon, package and PCB are analyzed separately and then combined with standard cascading technique) and integrated/global approach (where chip, package and PCB are analyzed as single entity in a co-simulation mode) are discussed and based on the results, guidelines are outlined. Read full article..

Spiral Inductor

Spiral Inductor
The 3rd Dimension: This inductive, mostly planar structure contains an air bridge. Read full article..

Dielectric breakdown simulations of a transformer On-Load Tap Changer

Dielectric breakdown simulations of a transformer On-Load Tap Changer
Leading manufacturers of Transformer On-Load Tap Changers (OLTC) ensure quality and secure functionality of their products by a high amount of physical tests. However, these tests are not performed in the environment of a transformer, i.e. not in a built-in situation and without connected tap-leads. The system as a whole transformer/OLTC/tap-leads) is finally tested in the transformer plant. The effect of the transformer and the tap-leads on the dielectric field strength may be investigated with the application of the CST EM STUDIO® electrostatic field solver. Read full article..
Back Back  

Your session has expired. Redirecting you to the login page...